1. Field of the Invention
The present invention concerns traction systems, especially in the railroad art, in general, and applies, more particularly, to a device and a method for direct current power supply to a traction system by means of converters from different alternating current or direct current voltages.
2. Description of the Prior Art
U.S. Pat. No. 5,629,591 concerns a high-availability multicurrent power supply system for railroad locomotives.
The above patent shows that traction systems using asynchronous motors, for example, require a direct current power supply.
The above patent also indicates that railroad vehicles are increasingly designed to travel on networks with different power supply voltages in different areas.
Voltages of 25 kV, 50 Hz, 15 kV, 16 2/3 Hz, 3 kV DC or 1.5 kV DC are found, for example.
Prior art devices for direct current power supply to a traction system by means of converters from different alternating current or direct current voltages use a dedicated converter for each power supply voltage.
In other words, prior art devices for direct current power supply to a traction system by means of converters from different alternating current or direct current voltages use, for example:
a Graetz bridge or a single-phase bridge with forced switching for alternating current power supplies, PA1 a reducer device, for example a chopper, if the DC power supply voltage is higher than the power supply voltage of the traction system, PA1 a booster device if the DC power supply voltage is less than the power supply voltage of the traction system.
One aim of the invention is a device and a method for direct current power supply to a traction system by means of converters from different alternating current or direct current voltages enabling the same converters to be used.